1. Field of the Invention
The present invention relates to an apparatus for cleaning various kinds of printing cylinders such as the blanket cylinder, impression cylinder, etc. of an offset press.
2. Prior Art
On printing with offset presses any foreign matter such as ink, paper dust, powder, dirt, etc. is very often found to adhere to the surface of the printing cylinder. Since such foreign matter is apt to deteriorate the quality of the printed products, in order to maintain such quality at high levels it is necessary to remove the above-described foreign matter adhered to the cylinder surface by frequently cleaning the surface of the printing cylinder during the preparation for the printing work or during the printing operation. Further, when the printing work is complete, the surface of the printing cylinder should be completely cleaned to remove the ink adhered thereto. For this purpose, prior art adopts cleaning systems such as a brush cleaning system, a wiping off system using non-woven fabric, a cleaning head system etc. Among them, as for the cleaning head system, the present applicant has already proposed the one shown in Japanese Patent Laying-open No. 77412/1993.
Although the system shown in Japanese Patent Laying-open No. 77412/1993 possesses many merits, the cleaning head is of a traveling type in which the traveling time becomes longer as the size of the printing machine is increased and hence the overall width of the printing cylinder is alsos increased, so that there was a problem that the cleaning, in general, takes a long time. On the other hand, an attempt to shorten the cleaning time by increasing the width of the cleaning head showed that since the required amount of air cannot be secured it is unreasonable from the structural viewpoint. In order to solve this problem the present applicant has proposed in Japanese Patent Application No. 13381/1993, an apparatus for cleaning printing cylinder in a cleaning a head system of a fixed type having a suction port.
The above-described proposal is found to be outstandingly effective in the case where use is made of an ink which is especially difficultly soluble in the cleaning liquid such as, for example, UV ink, or the like. Whereas, in the case of use of an ordinary ink, or the like, comparatively easily soluble in the cleaning liquid, the amount of the exhaust air so much increases that the cost of equipment runs up, the structure of the cleaning head is inevitably complicated, and the floor space to install becomes larger.
Further, in order that the cleaning liquid may be uniformly spread over the whole surface of the cleaning member it is necessary that the space between the supply tubes should be taken to be small, and since the amount of the cleaning liquid used should be as small as possible from the standpoint of the cost, it often happens that the supply pressure to the supply tubes becomes almost zero, in which case it is considerably difficult to make the amount of the liquid injected from the supply tubes uniform over the whole surface. In order to avoid this, it is necessary that the inside diameter of the nozzles of the supply tubes is made small (for example, less than 0.2 mm), but this was a problem in the fabrication.